TY - JOUR
T1 - Evolution of chaperome gene expression and regulatory elements in the antarctic notothenioid fishes
AU - Bilyk, Kevin T.
AU - Zhuang, Xuan
AU - Vargas-Chacoff, Luis
AU - Cheng, C. H.Christina
N1 - Publisher Copyright:
© 2020, The Author(s), under exclusive licence to The Genetics Society.
PY - 2021/3
Y1 - 2021/3
N2 - Confined within the cold-stable Southern Ocean, Antarctic notothenioid fishes have undergone an evolutionary loss of the inducible heat shock response (HSR), while facing perpetual low-temperature challenges to cellular proteostasis. This study examines how evolution in chronic cold has affected the shared cellular apparatus that mediates proteostasis under normal and heat stressed states. To deduce Antarctic-specific changes, we compared native expression levels across the full suite of chaperome genes and assessed the structural integrity of two crucial HSR regulators – Heat Shock Factor 1 (HSF1) that activates HSR, and heat shock elements (HSEs), the binding sites for HSF1 – between Antarctic fishes and the basal temperate notothenioid Eleginops maclovinus. Native expression levels of Antarctic fish chaperomes showed very modest changes overall, contrary to the common view of constitutive upregulation in the cold. Only a few cytosolic HSP70 genes showed greater transcription, with only the ancestrally-inducible HSPA6 strongly upregulated across all Antarctic species. Additionally, the constant cold has apparently not relaxed the selective pressures on maintaining HSF1 and HSEs in Antarctic fish. Instead, we found HSF1 experienced intensified selective pressure, with conserved sequence changes in Antarctic species suggesting optimization for non-heat-stress functional roles. HSEs of the HSP70 gene family have largely remained conserved in canonical sequence motifs and copy numbers as in E. maclovinus, showing limited impact of relaxed selective pressure. This study shows that evolution in chronic cold has led to both subtle and distinctive changes in the cellular apparatus for proteostasis and HSR, with functional consequences amenable to experimental evaluation.
AB - Confined within the cold-stable Southern Ocean, Antarctic notothenioid fishes have undergone an evolutionary loss of the inducible heat shock response (HSR), while facing perpetual low-temperature challenges to cellular proteostasis. This study examines how evolution in chronic cold has affected the shared cellular apparatus that mediates proteostasis under normal and heat stressed states. To deduce Antarctic-specific changes, we compared native expression levels across the full suite of chaperome genes and assessed the structural integrity of two crucial HSR regulators – Heat Shock Factor 1 (HSF1) that activates HSR, and heat shock elements (HSEs), the binding sites for HSF1 – between Antarctic fishes and the basal temperate notothenioid Eleginops maclovinus. Native expression levels of Antarctic fish chaperomes showed very modest changes overall, contrary to the common view of constitutive upregulation in the cold. Only a few cytosolic HSP70 genes showed greater transcription, with only the ancestrally-inducible HSPA6 strongly upregulated across all Antarctic species. Additionally, the constant cold has apparently not relaxed the selective pressures on maintaining HSF1 and HSEs in Antarctic fish. Instead, we found HSF1 experienced intensified selective pressure, with conserved sequence changes in Antarctic species suggesting optimization for non-heat-stress functional roles. HSEs of the HSP70 gene family have largely remained conserved in canonical sequence motifs and copy numbers as in E. maclovinus, showing limited impact of relaxed selective pressure. This study shows that evolution in chronic cold has led to both subtle and distinctive changes in the cellular apparatus for proteostasis and HSR, with functional consequences amenable to experimental evaluation.
UR - http://www.scopus.com/inward/record.url?scp=85094964937&partnerID=8YFLogxK
U2 - 10.1038/s41437-020-00382-w
DO - 10.1038/s41437-020-00382-w
M3 - Article
C2 - 33149264
AN - SCOPUS:85094964937
SN - 0018-067X
VL - 126
SP - 424
EP - 441
JO - Heredity
JF - Heredity
IS - 3
ER -